The present invention relates to an encrypted communication technique, and more particularly, to a technique of distributing an encryption key for use in encrypted communication within a group including a plurality of communication devices, to each of the communication devices.
Internet RFC/STD/FYI/BCP Archives, “RFC 3740—The Multicast Group Security Architecture”, [retrieved on Feb. 1, 2006], Internet URL: <http://www.faqs.org/rfcs/rfc3740.html> (hereinafter, referred to as Non-patent Document 1) discloses a technique in which a key server distributes a key and settings information (security association) for use in encrypted communication, to a plurality of communication devices that are registered in advance as a group, and each of the communication devices that perform encrypted communication uses the key and other information distributed from the key server, to perform encrypted communication with other communication devices within the group. By using the technique disclosed in Non-patent Document 1, each communication device can reduce the processing load generated by creating the key and the other information used in the encrypted communication.